The present invention relates generally to an improved fishing line, and more particularly to an improved nylon monofilament fishing line containing a reactive optical brightener which functions as an active component of the polymer chain performing a variety of valuable functions in the overall finished product. Thus, the invention relates to a nylon monofilament fishing line wherein the nylon monomer or mixture of monomers is polymerized in a conventional fashion, and wherein the polymerization is accomplished in the presence of a reactive component containing an optical brightener in situ.
Fishing lines prepared in accordance with the present invention are extremely stable with regard to color, and also have a high resistance to fading. Since the optical brightener is bound directly to the polymer chain or system, the permanent characteristics of the finished product are, of course, enhanced. In the polymeric system, the optical brightener component functions as a chain terminator and because of its reactant characteristics, and its uniform properties, greater uniformity of the physical properties of the finished product is obtained.
In the past, it has been traditional to mix a dye component with one or more nylon polymers in the form of pellets, with the mixture being tumbled for an extended period of time until uniformity is achieved. Thereafter, the pellets are passed through a conventional extruder to form a finished product. In accordance with the present invention, an optical brightener component is initially mixed with one, two, or perhaps more nylon monomers, with the mixture being heated until a reaction occurs between the optical brightener and the nylon monomers. In the substituted triazine and coumarin component, the reaction between the triazine-coumarin component and the nylon monomers is believed to occur at the site of the amine linking the triazine and coumarin portions, and thus the optically brightened characteristics are retained in the finished product. During the polycondensation and/or poly-addition reaction, a small quantity of the triazin-coumarin reactant is placed in admixture with one or more nylon monomers, with the entire mixture thereafter being subjected to polymerization reaction to form a finished nylon product useful as an extrudable product, or useful in admixture with other nylon constituents to form a product having exceptional optically brightened qualities and characteristics.
The initial reaction between the nylon monomer and the triazine-coumarin is continued until the triazine and coumarin component is substantially entirely reacted with the nylon monomer component, and this initial reactant product is then utilized as one component of a second reactant mixture including one or more additional nylon polymers. These "additional" nylon polymers may be from the same monomers which were employed in the preparation of the initial reaction product. The second reactant mixture is treated in the conventional fashion through an extruder until the final polyamide product is prepared. In certain instances, it may be desirable to utilize the triazine-coumarin component in a polycondensation reaction wherein this component is blended with a nylon monomer in an appropriate concentration to prepare a reactant mixture, and polymerized so as to provide in-situ formation of the optically brightened polymer desired.
The product obtained possesses good optical brightener and chroma stability, has good tensile properties, and is predictably controllable and stable in its properties, including flexural properties and characteristics. The reactant product formed from the reaction of a nylon monomer and the triazine-coumarin reactants is desirable for use in monofilament production for a variety of reasons as set forth herein. The monofilament, as a finished product, will normally be provided with a base chroma through incorporation of a pigment therein.
In conventional nylon production, spurious free monomer may be present in the finished product, with the spurious free monomer normally being water soluble. In application as a fish line, this feature is, of course, undesirable because of the constant alteration or change in physical properties of the product during use. The substituted triazine-coumarin component appears to react with the free monomer which may be present, with the finished product having been found to have a lower degree of water solubility and a greater degree of stearic hindrance. As a result, the monofilament appears to be less prone to monomer exudation. In other words, it appears that the substituted triazine-coumarin component functions as a scavenger to either react with or otherwise restrict freedom of any available free monomers or fragments thereof which may be created during the extrusion process.
As an additional advantage or characteristic, the triazine-coumarin component functions as a cyclic energy sink when coupled into the polymer structure, with the component functioning primarily as a chain terminator or end cap.
The utilization of the polymer of triazine-coumarin material and nylon contributes certain advantages in the processing. For example, the utilization of the polymer appears to alter the molecular weight distribution in the finished product, thereby providing a measure of control or "leveling" of the viscosity and other relevant characteristics in the finished product. As a further feature, it is believed that a catalytic effect occurs which alters polymer morphology and aids in production of a monofilament finished product. As has been indicated previously, the presence of the triazine-coumarin reactant product aids in stability of the finished monofilament product, including improved physical strength and stability, reduction of monomer bleeding, and an increase in chroma and optical brightening stability. It has been found that the triazine-coumarin nylon reactant product, such as may be referred to as a masterbatch, functions as a molecular lubricant for the final extrusion operation of the inter-polyamide material. This lubricant material is chemically similar and hence molecularly compatible with the ultimate constituent mixture. Inasmuch as the masterbatch has a significantly lower melt viscosity, the substance provides mobility and facilitates homogeneity when functioning as an intermolecular lubricant. Because of the nature of the overall ultimate reactant material, the masterbatch functions as a dispersing aid for the molten inter-polyamide material present in the extruder, thereby deterring phase separation. Each of these features has been found to significantly enhance the overall production capability.